Gypsum wallboard is used for forming interior and exterior walls of many building structures. The structure of the wallboard typically includes a gypsum composition which is generally prepared as a slurry composition, placed between two liners and set. Such wallboard gypsum compositions may be standard wallboard formulations or made to be water-resistant through use of various wax emulsions. Some of the more common commercial water-resistant wax emulsions involve use of particular wax components (which may include a single wax, or more typically, a blend of waxes), saponifying agent(s), emulsifier(s), stabilizer(s) and other additives. Of growing importance in the wallboard industry is the ever-increasing cost of manufacture of wallboard with respect to the rising cost of formulation components as well as increasing energy costs. For example, it is known in the art that manufacturing methods for formation of building products like gypsum wallboard that use emulsions in formation of the finished products, typically require a drying step or steps that consume energy. It would be beneficial to manufacture gypsum wallboard (standard and water-resistant) if the drying energy could be reduced for cost savings, particularly when energy demands are growing for manufacturers.
With respect to the manufacture of water-resistant wallboards, U.S. Pat. No. 5,437,722 describes a water-resistant gypsum composition and wax emulsion therefor, which includes a paraffin hydrocarbon having a melting point of about 40° C. to 80° C., about 1 to 200 parts by weight montan wax per 100 parts of the paraffin hydrocarbon, and about 1 to 50 parts by weight polyvinyl alcohol per 100 parts of the paraffin hydrocarbon. The use of montan wax in the wax emulsion for water-resistant wallboard has been very effective and provides excellent performance. Other water-resistant formulations based on natural waxes other than montan (such as carnauba and bees wax) and/or synthetic waxes (such as Fischer-Tropsch wax) have also been used as alternative water-resistant wax formulations. Most such formulations provide good water-resistance in gypsum wallboard formulations. However, some waxes typically used for such emulsions are in limited supply and/or are very expensive. Further, while strong water-resistance can be achieved, it would be desirable to achieve good water resistance properties in gypsum wallboard, while lowering the cost of components, increasing supply and/or reducing manufacturing costs.
Accordingly, there is a need in the art for compositions and methods that reduce energy costs associated with the manufacture of gypsum formulations, as well as a way to maintain and/or reduce energy costs associated with the manufacture of water-resistant gypsum formulations, while maintaining desirable formulation properties.